Sealing arrangements and assemblies are in widespread use in the oil and gas industry. One particular form of sealing assembly is the packer, which is generally used to seal an annular space within a wellbore, typically an annular space formed between a base pipe, such as a production tubular, and a bore wall. Packers may be used in zonal isolation operations, for example to permit targeted workover operations such as stimulation and fracing, to seal off zones to prevent water production, and the like.
Various forms of packer are currently in use, and typically comprise a sealing element, such as an annular rubber sealing element, arranged around an outer surface of a base pipe, wherein the sealing element is actuated or manipulated to radially extend into a sealing configuration. For example, inflatable packers are known in which one or more sealing elements are inflated to be radially extended. Mechanical packers are also known in which a mechanical arrangement is used to axially compress a sealing element to effect lateral expansion into a sealing configuration. Packers are also known in which a sealing element is formed of a swellable material, such as a swellable rubber, wherein the sealing element swells and expands upon exposure to a suitable activator to establish a seal. Swellable packers typically comprise a swellable material configured to swell upon exposure to an activator present within a wellbore, such as oil or water.
In many packer arrangements the sealing element is located between axially spaced rings which are secured to a base pipe. These rings may be provided for many purposes, such as to prevent axial movement or extrusion of the seal element when in use. In some arrangements, such as in mechanical packers, the rings may provide a reactive surface against which the seal element may be compressed during actuation. Furthermore, the rings may provide protection to the sealing element, for example during deployment into a wellbore. However, end regions of a sealing element adjacent to a ring may be vulnerable to damage or failure due to exposure to pressure and other conditions when in use. This failure may manifest itself as tearing of the rubber, for example tearing along an axial direction. Such failure has been observed to occur at unpredictable values, and often in proximity to the base pipe.